1. Field of the Invention
The present invention relates to a ratchet one-way clutch and a stator using the ratchet one-way clutch for use in an automatic transmission, constructional machinery, agricultural machinery or the like.
2. Description of the Related Art
FIG. 4 is a partially sectional view, taken in a radial direction, of a stator 61 provided with a conventional sprag one-way clutch.
A structure of the stator 61 will be explained hereinbelow. The stator 61 comprises an impeller 67, a one-way clutch 50 arranged on the inner peripheral side of the impeller 67, and a bush 80. Both axial ends of the one-way clutch 50 are supported by an inner radial portion 74 of the impeller 67 and the bush 80. Further, both axial ends of the stator 61 are rotatably supported by a pair of thrust needle bearings 71 and 74.
The sprag one-way clutch 50 assembled in the stator 61 comprises an inner race 52, an outer race 53 arranged so as to be rotatable relative to and concentric with the inner race 52, a plurality of sprags 54 arranged in an annular space defined by the inner race 52 and the outer race 53 for transmitting torque, a ribbon spring 55 rockably retaining the sprags 54 at regular intervals in a circumferential direction and biasing them in a meshing direction, and annular retainers 56 and 58 retaining the ribbon spring 55.
The bush 80 is a member serving as a bearing of the inner race 52 and the outer race 53, and is formed on the axially inner side thereof with an inner shoulder 81 and an outer shoulder 82 for receiving therein corners of the inner race 52 and the outer race 53, respectively. The inner race 52 slides on the inner shoulder 81. With the aid of both shoulders, the inner race 52 and the outer race 53 can be arranged concentrically with each other.
The stator 61 having the foregoing sprag one-way clutch transmits torque when a direction of relative rotation between the inner race 52 and the outer race 53 agrees with a meshing direction of the sprags 54, while it idles and thus does not transmit torque in case of a non-meshing direction of the sprags 54.
In recent years, the development has been active for reducing size, weight and cost of automobile parts such as an automatic transmission, and a one-way clutch is not exceptional. There has been proposed a ratchet one-way clutch responding to such a demand.
It is an object of the present invention to provide a ratchet one-way clutch which is reduced in the number of parts, reduced in size and improved in dimensional accuracy, and further provide a stator using such a ratchet one-way clutch. More specifically, it is an object of the present invention to provide a one-way clutch of a structure omitting the bush which has been required in the foregoing conventional one-way clutch, and further provide a stator using such a one-way clutch.
For accomplishing the foregoing objects, a ratchet one-way clutch according to the first aspect of the present invention comprises an inner race; an outer race arranged so as to be concentric with and rotatable relative to the inner race; concave portions formed along a circumferential direction on one of an outer periphery of the inner race and an inner periphery of the outer race; and a claw member to be fitted into one of the concave portions, a spring biasing the claw member relative to the concave portions, and a pocket formed on the other of the outer periphery of the inner race and the inner periphery of the outer race and receiving therein the claw member and the spring, wherein at least one of the inner race and the outer race has a bearing function.
In a ratchet one-way clutch according to another aspect of the present invention, a bearing portion is formed on at least one of the inner race and the outer race for allowing mutual sliding movement therebetween, and a predetermined clearance is provided between the inner race and the outer race.
In a ratchet one-way clutch according to another aspect of the present invention, the outer race is made of aluminum.
In a ratchet one-way clutch according to another aspect of the present invention, a projection for supporting the claw member axially is provided within the pocket.
A stator of the present invention uses any one of the foregoing ratchet one-way clutches.